Conventionally, in a library apparatus, an alignment adjustment is executed between a robot and an accommodating shelf that accommodates a cartridge to improve the precision of putting and taking the cartridge in/out of the accommodating shelf.
Concerning the positions of the above accommodating shelf and the robot relative to each other, Japanese Laid-Open Patent Publication No. 04-020404 discloses that: a two-dimensional relative position table is provided; positioning using a design value as a target position is executed for an accommodating shelf that is not registered in the two-dimensional relative position table; a relative position of the accommodating shelf is measured using a relative position detecting sensor; positioning is executed to the center of the accommodating shelf; the result of the relative position measurement is registered into the relative position table; and, thereby, a table is automatically created and updated (page 3, lines 2 to 11 in the lower column on the left, FIGS. 2 and 3, etc.).
Japanese Laid-Open Patent Publication No. 10-134458 discloses that: a first to a third reference flags provided to measure the degree of an inclination of an accessor, and a plurality of relative position flags attached to a cell drum are included; a flag sensor attached to an accessor hand mechanism detects the first to the third reference flags; and an inclination of each of a Y axis and a Z axis of the accessor is obtained (Abstract, FIG. 1, etc.).
Japanese Laid-Open Patent Publication No. 07-101509 discloses that: the position of a frame of an accommodating shelf 1 is accurately detected; a position correction is executed for a target position; the result thereof (position correction information) is stored in an accommodating shelf position information storing apparatus 13; and, thereby, time for positioning operation on and after the second time is reduced (Abstract, FIG. 4, ETC.).
An alignment adjustment of a library apparatus is at most executed in an on-site adjustment of the library apparatus. However, with the increase of the density of mounting cartridges in an accommodating shelf, a conveying operation of cartridges is influenced by variation of an installation environment and variation due to aging of a robot and, thereby, the conveying operation generates an error therein. Therefore, putting and taking a cartridge in/out of the accommodating shelf may not be accurately executed.
When such an unpredictable situation occurs, the system has to be stopped and alignments for all the cells need to be again taken similarly to the on-site adjustment and this work is very troublesome.
Japanese Laid-Open Patent Publications Nos. 04-020404, 10-134458 and 07-101509 include no suggestion and no disclosure for such a problem and also include no disclosure concerning means of solving the problem.